Tension equalizer



Aug. 25, 1925. r 1,550,881 I H. D. COLMAN;

TENSION E UALIZEB Filed Dec. 25. 1918 a {f0 wa/a b $2 2226! 22,

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Patented Aug. 25, 1925.

STTES PATENT OFFICE.

HOWARD D. GOLlVIAN, OF RO'OKFORD, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS,

TO BARBER-COLMAN COMPANY, OF ROCKFORD, ILLINOIS, A CORPORATION ILLINOIS. (1922.)

TENSION EQUALIZER.

Application filed December. 23, 1918. Serial No. 267,935.

To all whom it may concern:

Be it known that I, HOWARD D. CoLMAN, a citizen of the United States, residing at Rockford, in the county of lVinnebago and State of Illinois, have invented certain new and useful Improvements in Tension Equalizers, of which the following is a speclfication.

This invention has particular reference to machines for rewinding yarn from one container to another, the general object of the invention being to provide means for equalizing the tension of the yarn. The invention is especially applicable to machines wherein the yarn is drawn OK the end of the supply bobbin or other supply yarn mass. In drawing the yarn off the end of the bobbin, the yarn balloons. Most of the drag or resistance to winding is due to aerial resistance to the balloon. When the thread is drawn from the upper portion of the yarn mass, the balloon is shorter, and hence the aerial resistance is less than when a longer balloon is formed by the drawing of thread from the lower portion of the bobbin. The diameter of the supply yarn mass also affects the amount of drag, since when the yarn mass is of large diameter the balloon rotates less rapidly, and hence experiences less aerial resistance than when the diameter of the yarn mass is small and the balloon is rotating more rapidly.

The present invention provides means for adding a variable amount of tension to the tension due to the drag, the amount added being complementary to the tension due to the drag, whereby the tension of the thread in the region beyond the tension-adding device is approximately equalized or made constant.

When a thread having initial tension passes around a fixed guide the increase in tension in the thread will vary with the coefficient of friction between the thread and the guide and with the arc of contact. It will also be affected by the mass and speed of the thread and the radius of curvature of its path, as the centrifugal force of the thread will tend to hold it out of contact with the guide. For any given operating conditions, however, the mass and speed of the thread and the radius of curvature of its path will be approximately constant, so that the variation of the arc of contact is the only factor that need be considered.

According to my invention, I provide controlhng means operated by the thread and sensitive to the tension in the thread where it passes through such means, said controll ng means itself operating under all conditions of adjustment to multiply the tension of the thread coming to the controlling means by an approximately constant factor. There is also provided tensioning means for multiplying the tension in the thread by a variable factor, said tensioning means being controlled by the controlling means.

In the accompanying drawings, Figure 1 is a side elevation of a tension equalizer embodying the features of my invention. Figure 2 is a generally similar view with parts in section in the plane indicated by dotted line 22 of Fig. 3. Fig. 3 is a top; plan view, and Fig. 4: is a front end view. Fig. 5 is a detail view of one of the thread-guiding elements.

While it will be understood that the invention is applicable to various types of winding machines, it is herein illustrated as embodied in a machine for rewinding yarn from a bobbin A (which may be a filling-wind bobbin or a warp-wind bobbin) to form a yarn mass B, said yarn mass being rotated through peripheral contact with a rotary drum C. The parts B and C are represented merely diagrammatically. The yarn may be guided in any suitable manner in passing from the bobbin A to the yarn mass B. Herein is indicated a guide D located between the bobbin A and the tension equalizer. Said tension equalizer may be supported in any desired manner and in any suitable relation to the other elements of the machine. In this instance I have shown the tension equalizer as attached to a stationary supporting bar or plate 1, said bar having therein a thread-receiving notch 2 with a flaring upper end. Two brackets 3 and 4 are rigidly secured to the bar 1. These brackets rotatably support a shaft 5 upon which is rigidly mounted an arm 6. Fixed to said arm near the pivot 5 thereof is a pin 7. The thread is arranged torun over the shaft 5, under the pin 7, and oven a headed stud 8 carried by the bracket 3. The thread extends thence over a headed stud 9 on the bracket 3, under a stud 10 on the end of the arm 6, and thence through a guide 11 on the bracket 3. The guide 11 is open at one side for the lateral insertion of the thread. A torsion spring 12 surrounds the shaft 5 and bears at one end against the bracket 4. The other end of the spring 12 is hooked to engage a notched disk 13 secured to the arm 6, which disk affords means for adjusting the torsion of the spring. Said spring tends to swing the arm in the direction to draw a loop in the thread between the shaft 5 and the stud 8, and another loop between the stud 9 and the guide 11. Any suitable means may be provided to limit the movement of the arm 6 under the action of its spring. Herein is shown a buffer spring 14 located in position yieldingly to arrest the downward movement of the arm when the thread exhausts.

It will be seen that the arm 6 provided with the two pins 7 and 10 located at different distances from the axis 5, constitutes, in effect, two arms of different lengths. Preferably the arm 57 is made as short as practical considerations will permit, in or der to minimize the effect of the loop drawn by the pin 7 in supporting the arm 5-1O against the torsion of the spring 12. It may be here remarked that the supporting effect of the loop drawn by the pin 7 increases as the sides thereof approach parallelism.

The bracket 3 comprises an inclined web or flange 3 which extends from one wall of the notch 2 to a point opposite the open side of the guide 11. The notch 2 is so shaped as to provide a guide portion 1. When a thread is to be inserted into the tension equalizer, the operative raises the arm 6 into approximately the position indicated in dotted lines in Fig. 2, and passes the thread laterally into the notch 2 and the guide 11, the inclined flange 3 serving to guide the thread into place. If the thread be brought into contact with the portion 1 said portion guides the thread sidewise far enough so that it will pass under the pin 7. Similarly, the portion 11 of the guide 11 insures that the thread shall pass beneath the stud 10. The pin 7 is so located that the thread will slip beneath it without the necessity of raising the arm 6 excessively high.

In operation, the thread extends from the bobbin A, through the guide D, and thence in succession through the notch 2, over the shaft 5, under the pin 7, over the stud 8, over the stud 9, under the stud 10, and through the guide 11, passing thence, di rectly or indirectly, as the case may be, to the yarn mass B. The spring 12 keeps the stud 1O pressed against the thread and thus places tension upon the thread. As the dragfluctuates, the arm 6 rises and falls, but the sum of the arcs of contact of the thread with the studs 9' and 10 and the guide 11 remains substantially unchanged. As the arm 6 swings downwardly, the torsion of the spring decreases, but this is compensated for by the shortening of the effective lever arm, as will be apparent upon comparison of Figs. 1 and 2. Consequently the arm 5-1O places an approximately invariable amount of tension upon the thread. \Vhen the drag increases, the arm 6 rises against the torsion of the spring 12, thereby raising the pin 7 and thus decreasing the sum of the arcs of contact between the thread and the shaft 5, the pin 7 and the stud 8. The decrease of tension (due to such decrease in the arcs of contact between the thread and the parts 5, 7 and 8) and the decreased supporting efiect of the loop formed by the pin 7 offset the increase of tension due to the increased drag. lVhen the drag decreases, the arm 6 is swung downwardly by the spring 12, thereby lowering the pin 7 and causing an increase in the sum of the arcs of contact between the thread and the parts 5, 7 and 8, and an increase in the supporting effect of the loop drawn by the pin 7, thereby neutralizing the decrease in the drag. In this manner the tension of the thread in the region between the stud 8 and the yarn mass B is maintained approximately constant. The arm 6 is made as light as possible in order that it shall be very sensitive to variations in the drag.

The equilibrium of arm 6 depends on the force of the spring 12 and the counterbalancing forces exerted by the thread on pins 10 and 7. The torque around pivot 5 due to the force of the thread on pin 10 is much larger than the torque due to pin 7, because of the greater lever arm and the greater tension. Independently, therefore, of the effect of pin 7, a slight change in thread tension after leaving guide 8 will cause arm 6 to move until the changed arcs of contact with pins 5, 7 and 8 restore the original tension on pin 10. The response of the arm to instantaneous variations in tension, however, will tend to occur before the change in tension reaches pin 10 because with the arm in equilibrium, as soon as the change reaches pin 7, the equilibrium will be disturbed and the arm will begin to move.

The tension which the parts 5, 7 and 8 are capable of creating is sufficient to insure that the arm 6 shall not move into contact with the stop 14: during winding.

The points 5, 7 and 10 are not located in a straight line, and hence if the drag becomes great enough, the pin 7 may be lifted clear of the thread, in which position of course the parts 5, 7 and 8 place no tension on the thread.

I claim as my invention:

1. A tension equalizer having, in combination, a bracket, two pairs of thread-guides on said bracket, an arm pivoted at one end to said bracket, two pins located at different points in the length of said arm, each of said pins being arranged to pass between the members of one of said pairs of guides and bear upon the thread, and a spring for moving said arm in the direction to press the pins against the thread.

2. A tension equalizer having, in combination, a bracket, two pairs of thread-guides on said bracket, an arm pivoted at one end to said bracket, two pins located at different points in the length of said arm, each of said pins being arranged to bear upon the thread at a point between the members of one of said pairs of guides, and a spring for moving said arm in the direction to press the pins against the thread.

3. A tension equalizer having, in combination, a bracket, two pairs of thread-guides on said bracket, an arm pivoted to said bracket, two pins located at different points in the length of said arm, each of said pins being arranged to bear upon the thread at a point between the members of one of said pairs of guides, and a spring for moving said arm in the direction to press the pins against the thread, said thrcad-guides being adapted for the lateral placing of a thread thereon, and means to guide the thread into place beneath said pins.

4:. A tension equalizer having, in combination, two arms of different lengths rigidly connected together, guides for a thread against which thread said arms bear, and a spring for moving said arms against the tension of the thread, the shorter arm being arranged to have a variable are of contact with. the thread, and the longer arm serving to support the shorter arm against the tension of said spring.

5. A tension equalizer having, in combination, two guides for a thread, a pivoted arm arranged to bear against the thread between said guides to produce variable arcs of contact between the thread and said guides to render uniform the tension in the 6-. A tension equalizer having, in combination, a pivoted arm, resilient means for moving said arm in one direction, tensioning means carried at the end of said arm, and additional tensioning means carried near the pivot of said arm, said first mentioned tensioning means producing an approximately constant efi'ec't on the tension regardless of the position of the arm and said last mentioned tensioning means having a highly variable effect on the tension in difierent positions of the arm.

7 A tension equalizer having, in combination, two pairs of thread guides, a pivoted arm, two pins located adjacent opposite ends of said arm and arranged to press against the thread between the members of each pair of guides, said pins being so positioned with respect to the fulcrum of said arm that the torque due to the drag of the thread on one pin is negligible and on the other pin is relatively large.

8. A tension equalizer having, in combination, a movable member pivoted at one end, tensioning means carried by said member adjacent its pivoted end and having a variable effect on the tension and a relatively small effect on the position of said member, and controlling means carried by said member adj acent its free end and having an approximately constant efi'ect on the tension and operating primarily to control the position of said member.

In testimony whereof, I have hereunto set my hand.

HOWARD D. COLMAN. 

